The primary objective of this research is to study the organization of prefrontal cortex with the goal of understanding the anatomical bases of the neural integrations which occur in each of its subdivisions. The approach combines several techniques for analyzing the organization of neuronal pathways, including anterograde degeneration and anterograde and retrograde axonal transport, in the prosimian primate Galago senegalensis. One series of experiments is aimed at determining the cellular origins and terminal distributions of projections to the thalamic relay nucleus of prefrontal cortex. Specifically, we would like to learn which functional systems originate projections to the medial dorsal nucleus of the dorsal thalamus, and precisely how these projections are distributed among its subdivisions. Likewise, a second series of experiments is aimed at determining how subdivisions of the medial dorsal nucleus, in concert with other regions of the brain, relate to the laminae of circumscribed subdivisions of the prefrontal cortex. Another series of experiments uses deoxyglucose autoradiography to analyze the functional representation of the olfactory system in subdivisions of the prefrontal cortex.